The changes mean that industry will have to file 22,000 fewer reports each year, reducing an important public monitoring tool on industrial emissions, the Government Accountability Office says in a report.

The EPA rushed to complete the changes because of "pressure" from the White House Office of Management and Budget to reduce the regulatory burdens on industry, the study says. The White House overstated the cost-savings to industry of making the changes, it added.

"The EPA administrator expedited the process in order to meet a commitment to OMB," which had pushed to reduce the paperwork burden on industry by the end of 2006, the GAO said.

For more than two decades, industries and businesses have had to disclose to the EPA the amount of toxic chemicals they produce, store, and discharge. Communities, watchdog groups, local neighborhoods, and the Internal Revenue Service have used the data.

Last December, the EPA reduced the amount of information that needed to be disclosed in the Toxics Release Inventory Report, or TRI, process. Companies were allowed to file shorter, less detailed forms if they used less than 5,000 pounds of toxic chemicals or released less than 2,000 pounds. Previously more detailed information had to be provided in longer forms if there was as little as 500 pounds, a threshold that the new rule maintains only for some of the most dangerous chemicals.

Senator Barbara Boxer, a Democrat of California, chairwoman of the Environment and Public Works Committee, said the GAO report "confirms the serious flaws" in the reporting requirement." The public has a right to know about toxic pollution in local communities," she said in a statement.

Senator Frank Lautenberg, a Democrat of New Jersey, said the report, which he and Boxer had requested, "makes clear the Bush administration is . . . letting facilities hide critical data about toxic chemicals."

The EPA, in a response included within the report, said it disagreed with the GAO's conclusions and that the rule changes included new incentives for industry to reduce the amount of toxic chemicals it uses.

"EPA believes fully that all appropriate and necessary analyses were conducted," wrote Molly O'Neill, the agency's assistant administrator and chief information officer.

The EPA estimated the changes would save industry and businesses $6 million annually.

But the GAO said that analysis "masked the disproportionately large impacts" the reporting changes would have on individual communities and that the EPA's estimated cost savings were based on outdated information from the Office of Management and Budget and overstated the savings by as much as 25 percent.